Not Enough Sleep Could Increase Stroke Risk: Study

Most of us are aware of the main risk factors for a stroke -- smoking cigarettes, leading a sedentary lifestyle, having high blood pressure and/or cholesterol, among others. But now, new research suggests not getting enough sleep could also raise your risk.

A study presented at the SLEEP 2012 conference shows that middle- to older-aged people who regularly get fewer than six hours of sleep a night have an increased stroke risk, even if they don't have a history of stroke, aren't overweight and don't have an increased risk for obstructive sleep apnea.

"These people sleeping less than six hours had a four times increased risk of experiencing these stroke symptoms compared to their normal weight counterparts that were getting seven to eight hours," study researcher Megan Ruiter, of the University of Alabama at Birmingham, told HuffPost.

The study included 5,666 people who were examined by researchers over a three-year period for the symptoms of stroke, risk factors for stroke, symptoms of depression and demographics.

Even though the researchers found a link between getting fewer than six hours of sleep a night and stroke among normal weight people, they did not find such a link in the overweight and obese study participants.

"I was expecting that we were going to see some sort of association, but I really wasn't expecting it in the normal weight folks and not the overweight folks," Ruiter said.

Ruiter added that short sleep may have this effect on stroke risk by acting on other, known risk factors: increasing blood pressure, spurring inflammation and altering metabolic hormones. "Once these traditional stroke risk factors are present, then perhaps they become stronger risk factors than sleep duration alone," Ruiter said in a statement.

Because sleep is something that people can make a point to get more of -- meaning it's a "modifiable risk factor" -- the study findings could provide a basis for recommending sleep-based treatments to prevent stroke, she said.

"A lot of people say that when things get stressful and schedules get tight sleep is the first thing to get sacrificed," Ruiter said. "It turns out that it's a lot more problematic than we previously realized."

Earlier this year, a study presented at the American Stroke Association's International Stroke Conference showed that sleep apnea -- a sleep condition where a person suddenly stops breathing during sleep -- is linked with a symptomless form of stroke, called silent stroke.

"We found a surprisingly high frequency of sleep apnea in patients with stroke that underlines its clinical relevance as a stroke risk factor," study researcher Dr. Jessica Kepplinger said in a statement.

Silent strokes don't have any symptoms, meaning a person typically doesn't know he or she has suffered one, ABC News reported. Having multiple silent strokes is linked with memory loss, difficulties with walking and mood problems.